lint fixes and add rubygems_package param
Lint fixes and rubygems_package override

This change allows for specifying the package for rubygems, in the same
way as the ruby_package param. This is useful specifically on Ubuntu
where 1.9 (and it's associated rubygems) is a separate package,
not a version of the ruby package.
added tests for the rubygems_package param
update README with rubygems_package docs
Add gem testing dependencies and travis config

The repo is setup to build in Travis, but without the dependencies the
build fails.
as per pull request comment, update puppet versions for travis
correct typo in README
as per pull request, remove Gemfile.lock